Is there an online academy that is interactive and you can learn TI Basic?
as far as i know, no. there is no one way to program in ti basic, there are many different routes you can take to reach the same result. there are a lot of tutorials and the wiki offered here has a chapter based programming guide. if you ever do need help, you can always press the discuss button at the bottom of a wiki page to start a forum thread on it. that's probably the closest to "interactive" you can get.
The Silver Phantom welcomes you
There's tons of different books and guides and of course, here, to learn how to program TI-BASIC. Don't worry, it's a lot easier than it looks. xD All you need to do is start from the bottom and work your way up, you'll be good at it in no time.